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Monday, March 27, 2017

How To Identify Master Node in RAC

HOW TO IDENTIFY MASTER NODE IN RAC

Key points to note about master node :-

1) Master node has the least Node-id in
the cluster. Node-ids are assigned to the nodes in the same order as the
nodes join the cluster. Hence, normally the node which joins
the cluster first is the master node

2) CRSd process on the Master
node is responsible to initiate the OCR backup as per the backup policy

3) Master node is also
responsible to sync OCR cache across the nodes

4) CRSd process on the master node reads
from and writes to OCR on disk

5) In case of node eviction, The cluster
is divided into two sub-clusters. The sub-cluster containing fewer no. of nodes
is evicetd. But, in case both the sub-clusters have same no. of nodes, the
sub-cluster having the master node survives whereas the other sub-cluster is
evicted

6) If master node got evicted/rebooted,
another node become master

7) Master node can be
found by multiple ways, some of them are listed as